MX31 clkdev support

This patch adds clkdev support for i.MX31. This is done in a
similar way done previously for i.MX27

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/plat-mxc/Kconfig b/arch/arm/plat-mxc/Kconfig
index ed5ab8e..17d0e99 100644
--- a/arch/arm/plat-mxc/Kconfig
+++ b/arch/arm/plat-mxc/Kconfig
@@ -22,6 +22,7 @@
 config ARCH_MX3
 	bool "MX3-based"
 	select CPU_V6
+	select COMMON_CLKDEV
 	help
 	  This enables support for systems based on the Freescale i.MX3 family